Displays include televisions, computer monitors, home cinema displays, digital cinema displays, dedicated displays on devices such as tablet computers, cellular telephones, digital cameras, copiers, industrial controls, specialized displays such as displays for medical imaging, virtual reality, vehicle simulation and the like. Colour displays may be used to display colour images specified in image data.
Displays may incorporate any of a wide variety of underlying display technologies. For example, displays may comprise: cathode ray tube (CRT) displays; backlit liquid crystal displays (LCDs); plasma displays; light-emitting diode (LED) displays; organic LED displays (OLED displays); laser projectors; digital mirror device (DMD) displays; and electroluminescent displays. Within any of these general technologies a wide variety of different constructions and compositions for light-emitting and/or filtering elements are possible. As a result, different displays may have capabilities that differ significantly in areas such as, for example, the range of different colours (i.e. gamut) that can be displayed, the range in luminance values that can be displayed (i.e. the dynamic range of the display), and the like. The range of the display's capabilities in one area may be defined as a particular video range of the display.
Image data (including video data and still image data) can have any of a wide variety of different formats. Some example image data formats are: RGB, YLU, GIF, TIFF, JPEG/JIF, PNG, BMP, PDF, RAW, FITS, MPEG, MP4, high dynamic range (HDR) formats such as BEF, HDRi, JPEG XR, JPEG HDR, RGBE, ScRGB and many others. Image data formats can have capabilities that differ significantly in areas such as, for example, the range of different colours (i.e. gamut) that can be specified, the range of luminance levels (i.e. dynamic range) that can be specified, the number of discrete colours within the gamut that can be specified, the number of discrete luminance levels that can be specified, and the like. Some image data formats have multiple versions having different capabilities. The range of the image data format's capabilities in one area (e.g. chrominance or luminance) may be defined as a particular video range of the image data format. The range of values (e.g. chrominance or luminance values) specified by specific image data may be defined as the particular video range of the image data.
Colours may be specified in many different colour spaces. Some examples include RGB, HSV, LUV, YCbCr, YIQ, YCbCr, xvYCC, HSL, XYZ, CMYK, CIE LAB, IPT, and others. Different image data formats may specify colours in different colour spaces.
It may be desirable to display image data on a display having a video range which may not match the video range of the image data. There is a need for systems, apparatus and methods capable of adjusting image data to provide a good viewing experience in cases where there is a mismatch between the image specification characteristics of image data and image reproduction characteristics of a display.